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Re: [PERFORM] Posible planner improvement?

From: "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
To: Decibel! <decibel(at)decibel(dot)org>
Cc: Richard Huxton <dev(at)archonet(dot)com>,PG Hackers <pgsql-hackers(at)postgresql(dot)org>,Luke Lonergan <LLonergan(at)greenplum(dot)com>, albert(at)sedifa(dot)com
Subject: Re: [PERFORM] Posible planner improvement?
Date: 2008-05-25 08:21:33
Message-ID: 20080525082133.GB27965@cuci.nl (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
Decibel! wrote:
>For reference, the original query as posted to -performance:

>select * from t1, t2 where t1.id > 158507 and t1.id = t2.id;

>That took > 84 minutes (the query was a bit longer but this is the  
>part that made the difference) after a little change the query took  
>~1 second:

Just out of curiosity, would predefining the order of join have solved
the issue, as in:

a. select * from t1 join t2 using(id) where t1.id > 158507;
vs.
b. select * from t2 join t1 using(id) where t1.id > 158507;

I'd expect a to be faster than b, is it?
-- 
Sincerely,                                                          srb(at)cuci(dot)nl
           Stephen R. van den Berg.
"Technology is stuff that doesn't work yet."   --  Bran Ferren
"We no longer think of chairs as technology."  --  Douglas Adams

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